I would like to send a signal via a wire about 30-40 meters length (max). The signal is produced by an AVR PWM output (10bit, ~20Khz, 0-5V) and it contains audio data. I can send the PWM signal as it has or pass it from a sallen-key active filter before send it.
I would like to ask a question about the advantages and the disadvantages of transfering the signal. Which method is better for my case ?
- PWM signal as it has or
- AUDIO signal (after the sallen-key filter)
If the better sollution is the second one, then what kind of audio output is better DC (as it has) or AC (using a capacitor in series) ?